Through a collaboration of researchers from Resources for the Future, the U.S. Geological Survey National Water-Quality Assessment (NAWQA), and Pennsylvania State University, scientists can now estimate sources and losses of organic carbon in surface waters in the United States by using a new carbon model. Streams act as important sinks for organic carbon, and any planning to mitigate rising atmospheric carbon dioxide concentrations should consider the role that rivers play in the carbon cycle.

The SPARROW Total Organic Carbon model was estimated using a comprehensive national set of geospatial data, including long-term monitoring data from 1,125 stream locations and detailed information on land cover, climatic conditions, soils and stream networks.

The importance of organic carbon on water quality has long been recognized, but challenges remain in:

partitioning how much of the organic carbon that is stored in lakes, rivers, and streams comes from allochthonous sources (produced in the terrestrial landscape) versus autochthonous sources (produced in-stream by primary production;

and
understanding the importance of surface water sources of carbon to regional carbon balances.

This study is supported by the USGS National Water-Quality Assessment Program and the National Climate Effects Network. Hydrologic modeling and analysis tools, such as this one, are important components of both of these programs.